Help with kinetics and conservation problem thanks!

An object of mass m1 moving with velocity v1 in three dimensions collides with
a second object of mass m2 moving with velocity v2. We are interested in solving
for the velocities of the objects after the collision. There are six unknown values
f (v1x)f ; (v1y)f ; (v1z)f ; (v2z)f ; (v2y)f ; (v2z)f g in three dimensional.

(1) If no additional information is given, how many conservation equations
do we have? Do we have enough information to solve for the six unknown values?
If not, how many additional equations or additional pieces of information do we
need to solve for the six unknown values?

(2) If we know that the kinetic energy of the two objects is conserved (a.k.a.
totally elasticcollision), how many conservation equations do we have? Do we
have enough information to solve for the six unknown values? If not, how many
additional equations or additional pieces of information do we need to solve for
the six unknown values?

(3) If we know that the two objects are stuck together (,a.k.a. totally in-
elasticcollision) how many conservation (or other conservation-like) equations
do we have? Do we have enough information to solve for the six unknown val-
ues? If not, how many additional equations or additional pieces of information
do we need to solve for the six unknown values?

Note: do not answer this question with answers like six, yes, none. While
you do not need to write down the conservation equations, you do need to at
least mention what the equations are.